Heat-resistant rubber composition

ABSTRACT

A heat-resistant rubber composition of the invention is a vulcanizable composition comprising a specific ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) and an organic peroxide (B). This heat-resistant composition has high crosslinking efficiency given by the organic peroxide and high modulus, and can provide a vulcanized rubber molded product of excellent resistance to environmental deterioration such as thermal aging resistance. The other heat-resistant rubber composition of the invention is a vulcanizable composition comprising 100 parts by weight of a specific ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) composed of ethylene, an α-olefin or 3 to 20 carbon atoms and a nonconjugated polyene which is a vinyl end group-containing norbornene compound, 0.2 to 5 parts by weight of an amine type anti-aging agent (C) and/or a hindered phenol type anti-aging agent (D), 1 to 10 parts by weight of a sulfur type anti-aging agent (E) and an organic peroxide (B). This heat-resistant rubber composition can provide a vulcanized rubber molded product showing not only excellent mechanical properties and electrical properties and but also prominently high thermal aging resistance.

TECHNICAL FIELD

The present invention relates to a heat-resistant rubber compositioncomprising an ethylene-α-olefin-nonconjugated polyene copolymer rubber.More particularly, the invention relates to a vulcanizableheat-resistant rubber composition having high crosslinking efficiencygiven by an organic peroxide and capable of providing a vulcanizedrubber molded product showing not only excellent mechanical andelectrical properties but also prominently high thermal agingresistance, specifically a vulcanizable heat-resistant rubbercomposition having extremely good fluidity (molding processability).

BACKGROUND ART

Crosslinking of ethylene-α-olefin copolymer rubbers is carried out usingnot sulfur, but organic peroxides, because the copolymers have no doublebond in their main chains. The rubbers have been used for automotiveparts, industrial packing, electrical wires and electrical wireconnecting parts, but these parts are desired to be produced at a lowcost. For reducing the production cost, it is included to decrease anamount of an organic peroxide crosslinking agent. In these methods,however, the crosslinking is insufficiently performed, resulting inproblems of low modulus and poor resistance to permanent set.

On the other hand, since ethylene-α-olefin-nonconjugated diene copolymerrubbers prepared by copolymerizing ethylene, α-olefins and nonconjugatedpolyenes have higher crosslinking efficiency given by an organicperoxides than ethylene-α-olefin copolymer rubbers, the amount of theorganic peroxide can be decreased. However, with respect to theethylene-α-olefin-nonconjugated diene copolymer rubber using1,4-hexadiene, dicyclopentadiene or 5-ethylidene-2-norbornene as thenonconjugated diene, crosslinking is still insufficiently performed, andthe thermal aging resistance is low because a large number of doublebonds remain after the crosslinking reaction.

By the way, ethylene-propylene copolymer rubbers orethylene-propylene-diene copolymer rubbers formed by a diene such asethylidene norbornene, cyclopentadiene or 1,4-hexadiene have excellentmechanical and electrical properties. Moreover, they shows high thermalaging resistance and weathering resistance because they have no doublebond in their main chains. Therefore, these rubbers have been widelyused for automotive parts, industrial rubber parts, electrical parts andcivil engineering and building materials, as described above. In thefields of automotive parts and electrical parts and the like, however,the ethylene-propylene copolymer rubbers and theethylene-propylene-diene copolymer rubbers have been recently desired tohave much higher thermal aging resistance and fluidity (moldingprocessability).

In order to improve a fluidity of the ethylene-propylene copolymerrubbers, a method of adding oils as plasticizers to the copolymerrubbers is generally utilized. In the ethylene-propylene copolymerrubbers prepared utilizing this method, however, there reside problemsthat the thermal aging resistance of the molded product is lowered andan oil transfer phenomenon (i.e., bleeding) takes place to markedlyreduce commercial values.

Further, a method of adding plastics such as polyethylene to theethylene-propylene copolymer rubbers is also utilized to improve thefluidity. In the ethylene-propylene copolymer rubbers prepared utilizingthis method, however, there generally reside problems of low heatresistance and poor elastomeric properties.

Furthermore, an ethylene copolymer rubber composition which is impartedwith good processability (fluidity) by blending anethylene-α-olefin-polyene copolymer rubber having a different molecularweight is proposed in Japanese Patent Publication No. 14497/1984.However, this rubber composition does not show such high thermal agingresistance as desired.

On the other hand, some examples of conventional methods to improve thethermal aging resistance are described below.

(1) An anti-aging agent is added to the ethylene-propylene copolymerrubber or the ethylene-propylene-diene copolymer rubber.

(2) Since a breakage of a polymer main chain, as the heat deteriorationreaction, easily takes place, an ethylene-propylene copolymer rubberwhich is softened after the heat deterioration and anethylene-propylene-polyene copolymer rubber which is cured after theheat deterioration are blended.

(3) The diene content in the ethylene-propylene-polyene copolymer rubberis decreased.

A large number of combinations of these methods are also proposed.

For example, Japanese Patent Laid-Open Publication No. 23433/1985proposes a rubber composition for sulfur vulcanization which is preparedby blending 100 parts by weight of an ethylene-α-olefin-diene copolymerrubber having an iodine value of 5 to 12, 1 to 10 parts by weight of aphenol compound and 1 to 4 parts by weight of an imidazole compound.

The compositions proposed in the publication are improved in the thermalaging resistance, but the level thereof is not satisfactory in the usesfor automotive parts and electrical parts, so that the thermal agingresistance should be much more improved.

In Japanese Patent Laid-Open Publication No. 108240/1989, aheat-resistant rubber composition comprising an ethylene-α-olefincopolymer rubber, polyorganosiloxane and a silica type filler treatedwith a silane compound is disclosed as a heat-resistant rubbercomposition of high thermal aging resistance. The rubber compositiondisclosed in the publications are obviously improved in the thermalaging resistance, but the level thereof is not satisfactory in the usesfor automotive parts and electrical parts, so that the thermal agingresistance should be much more improved. Moreover, these compositions donot show such high fluidity (molding processability) as desired.

Accordingly, development of a vulcanizable heat-resistant rubbercomposition having high crosslinking efficiency and capable of providinga vulcanized rubber molded product of high thermal aging resistance hasbeen desired.

Further, development of a vulcanizable heat-resistant rubber compositioncapable of providing a vulcanized rubber molded product of prominentlyhigh thermal aging resistance without losing excellent mechanical andelectrical properties inherent in the ethylene-propylene copolymerrubber or the ethylene-propylene-diene copolymer rubber has been alsodesired.

Furthermore, development of a vulcanizable heat-resistant rubbercomposition showing high fluidity (molding processability) and capableof providing a vulcanized rubber molded product of prominently highthermal aging resistance without losing excellent mechanical andelectrical properties inherent in the ethylene-propylene copolymerrubber or the ethylene-propylene-diene copolymer rubber has been alsodesired.

The present invention is intended to solve such problems associated withthe prior art as described above, and it is an object of the inventionto provide a heat-resistant rubber composition being vulcanizable andhaving high crosslinking efficiency and capable of providing avulcanized rubber molded product of high thermal aging resistance.

It is another object of the invention to provide a heat-resistant rubbercomposition being vulcanizable and capable of forming a vulcanizedrubber molded product showing not only excellent mechanical andelectrical properties but also prominently high thermal agingresistance.

It is a further object of the invention to provide a heat-resistantrubber composition being vulcanizable and having extremely good fluidityand capable of forming a vulcanized rubber molded product showing notonly excellent mechanical and electrical properties but also prominentlyhigh thermal aging resistance.

DISCLOSURE OF THE INVENTION

A heat-resistant rubber composition according to the invention is avulcanizable composition comprising:

an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) composedof ethylene, an α-olefin of 3 to 20 carbon atoms and a nonconjugatedpolyene, and

an organic peroxide (B); and having vulcanizable properties,

said ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) havingthe following properties:

(1) a molar ratio of ethylene to the α-olefin of 3 to 20 carbon atoms isin the range of 40/60 to 95/5 (ethylene/α-olefin),

(2) the nonconjugated polyene is 5-vinyl-2-norbornene,5-isopropenyl-2-norbornene or 5-isobutenyl-2-norbornene,

(3) the nonconjugated polyene content is in the range of 0.5 to 50 g/100g in terms of an iodine value, and

(4) an intrinsic viscosity [η], as measured in decalin at 135° C., of0.1 to 10 dl/g.

The other heat-resistant rubber composition according to the inventionis a vulcanizable composition comprising:

[I] an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)composed of ethylene, an α-olefin of 3 to 20 carbon atoms and anonconjugated polyene, in an amount of 100 parts by weight,

[II] an amine type anti-aging agent (C) composed of diphenylaminesand/or phenylenediamines, in an amount of 0.2 to 5 parts by weight,and/or a hindered phenol type anti-aging agent (D) in an amount of 0.2to 5 parts by weight,

[III] a sulfur type anti-aging agent (E) in an amount of 1 to 10 partsby weight, and

[IV] an organic peroxide (B);

said ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) havingthe following properties:

(1) a molar ratio of ethylene to the α-olefin of 3 to 20 carbon atoms isin the range of 40/60 to 95/5 (ethylene/α-olefin),

(2) the nonconjugated polyene is 5-vinyl-2-norbornene,5-isopropenyl-2-norbornene or 5-isobutenyl-2-norbornene,

(3) the nonconjugated polyene content is in the range of 0.5 to 50 g/100g in terms of an iodine value, and

(4) an intrinsic viscosity [η], as measured in decalin at 135° C., of0.1 to 10 dl/g.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) may bean ethylene-α-olefin-nonconjugated polyene copolymer rubber having beengraft-modified with an unsaturated carboxylic acid or its derivative.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) may bea blend of:

[I] an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1)having an intrinsic viscosity [η], as measured in decalin at 135° C., of1 to 10 dl/g, in an amount of 30 to 95 parts by weight, and

[II] an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A2)having an intrinsic viscosity [η], as measured in decalin at 135° C., of0.1 to 5 dl/g, this intrinsic viscosity being different from theintrinsic viscosity of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A1), in an amount of 5 to 70 parts by weight,

the total amount of said components (A1) and (A2) being 100 parts byweight.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1) hasthe following properties:

(1) said copolymer rubber is a copolymer rubber composed of ethylene, anα-olefin of 3 to 20 carbon atoms and a nonconjugated polyene;

(2) a molar ratio of ethylene to the α-olefin of 3 to 20 carbon atoms isin the range of 40/60 to 95/5 (ethylene/α-olefin);

(3) the nonconjugated polyene is 5-vinyl-2-norbornene; and

(4) the nonconjugated polyene content is in the range of 0.5 to 50 g/100g in terms of an iodine value.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) hasthe following properties:

(1) said copolymer rubber is a copolymer rubber composed of ethylene, anα-olefin of 3 to 20 carbon atoms and a nonconjugated polyene;

(2) a molar ratio of ethylene to the α-olefin of 3 to 20 carbon atoms isin the range of 40/60 to 95/5 (ethylene/α-olefin);

(3) the nonconjugated polyene is 5-vinyl-2-norbornene,5-isopropenyl-2-norbornene or 5-isobutenyl-2-norbornene; and

(4) the nonconjugated polyene content is in the range of 0.5 to 50 g/100g in terms of an iodine value.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) whichis a blend of the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A1) and the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A2) has:

(i) a Mooney viscosity [ML₁₊₄(100° C.)] of 5 to 180,

(ii) a molar ratio of ethylene to the α-olefin of 40/60 to 95/5(ethylene/α-olefin), and

(iii) a nonconjugated polyene content of 0.5 to 50 g/100 g in tems of aniodine value.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1) and/orthe ethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) may bean ethylene-α-olefin-nonconjugated polyene copolymer rubber having beengraft-modified with an unsaturated carboxylic acid or its derivative.

When the ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)which is a blend of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A1) and the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A2) is used, a vulcanizable heat-resistant rubbercomposition having extremely good fluidity and capable of forming avulcanized rubber molded product showing not only excellent mechanicaland electrical properties but also prominently high thermal agingresistance and high crosslinking efficiency can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

A heat-resistant rubber composition according to the invention isdescribed in detail hereinafter.

A heat-resistant rubber composition according to the invention is avulcanizable rubber composition comprising:

an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) and anorganic peroxide (B).

The other heat resistant rubber composition of the invention accordingto the invention is a vulcanizable rubber composition comprising:

[I] an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A),

[II] an amine type anti-aging agent (C) and/or a hindered phenol typeanti-aging agent (D),

[III] a sulfur type anti-aging agent (E), and

[IV] an organic peroxide (B).

Ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) is arubber prepared by copolymerizing ethylene, an α-olefin of 3 to 20carbon atoms and a nonconjugated polyene.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) may bea blend of ethylene-α-olefin-nonconjugated polyene copolymer rubbers(A1) and (A2) each of which is by copolymerizing ethylene, an α-olefinof 3 to 20 carbon atoms and a nonconjugated polyene.

Examples of the α-olefins of 3 to 20 carbon atoms include propylene,1-butene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene,1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene,9-methyl-1-decene, 11-methyl-1-dodecene and 12-ethyl-1-tetradecene.These α-olefins are used singly or in combination of two or more kinds.

Of the above α-olefins, preferred are propylene, 1-butene, 1-hexene,1-octene and 1-decene.

In the ethylene-α-olefin-nonconjugated polyene copolymer rubbers (A),(A1) and (A2), a molar ratio of ethylene to the α-olefin of 3 to 20carbon atoms is in the range of 40/60 to 95/5 (ethylene/α-olefin),preferably 50/50 to 90/10, more preferably 55/45 to 85/15, particularlypreferably 55/45 to 80/20.

The nonconjugated polyene of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A) is a vinyl end group—containing norbornene compoundwhich includes 5 -vinyl- 2 -norbornene, 5 -isopropenyl- 2 -norbornene,and 5 -isobutenyl- 2 -norbornene, or 5 -methylene- 2 -norbornene.

The nonconjugated polyene of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A1) is 5-vinyl-2-norbornene, and the nonconjugatedpolyene of the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A2) is 5-vinyl-2-norbornene, 5-isopropyenyl-2-norbornene or5-isobutenyl-2-norbornene. Any of the nonconjugated polyene is a vinylend group-containing norbornene compound. used in combination with thefollowing nonconjugated polyene compounds:

chain nonconjugated diene compounds, such as 1,4-hexadiene,3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene,4,5-dimethyl-1,4-hexadiene and 7-methyl-1,6-octadiene;

cyclic nonconjugated diene compounds, such as methyltetrahydroindene,5-ethylidene-2-norbornene, 5-methylene-2-norbornene,5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene and6-chloromethyl-5-isopropenyl-2-norbornene; and

triene compounds, 2,3-diisopropylidene-5-norbornene,2-ethylidene-3-isopropylidene-5-norbornene and2-propenyl-2,2-norbornadiene.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) used inthe invention has a nonconjugated polyene content of 0.5 to 50,preferably 1 to 40 in terms of an iodine value.

When the nonconjugated polyene content is less than 0.5 in terms of aniodine value, the crosslinking efficiency is lowered. When thenonconjugated polyene content exceeds 50, the resulting rubbercomposition has poor resistance to environmental deterioration.

The nonconjugated polyene content is an indication of a vulcanizing ratein the vulcanization process. Together with other properties such as anintrinsic viscosity and an ethylene content, the nonconjugated polyenecontent contributes to the preparation of a copolymer rubber having goodfluidity (molding processability) and high strength.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) used inthe invention has an intrinsic viscosity [η], as measured in decalin at135° C., of 0.1 to 10 dl/g, preferably 0.5.to 7 dl/g, more preferably0.9 to 5 dl/g.

When the ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)having an intrinsic viscosity within the above range is used, a rubbercomposition showing good fluidity (molding processability) and capableof providing a vulcanized rubber of excellent properties can beobtained.

The intrinsic viscosity [η] is an indication of a molecular weight ofthe ethylene-α-olefin-nonconjugated polyene copolymer rubber (A).Together with other properties such as the nonconjugated polyenecontent, the intrinsic viscosity contributes to the preparation of acopolymer rubber having excellent fluidity (molding processability),strength, heat resistance and weathering resistance.

In the blend of the ethylene-α-olefin-nonconjugated polyene copolymerrubbers (A1) and (A2), that is used as theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), each ofthe copolymer rubbers (A1) and (A2) has a nonconjugated polyene contentof 0.5 to 50, preferably 1 to 40 in terms of an iodine value.

When the ethylene-α-olefin-nonconjugated polyene copolymer rubbers (A1)and (A2) having a nonconjugated polyene content within the above rangeare used, a rubber composition capable of providing a vulcanized rubbermolded product of prominently high thermal aging resistance can beobtained.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1) has anintrinsic viscosity [η], as measured in decalin at 135° C., of 1 to 10dl/g, preferably 2 to 6 dl/g, more preferably 3 to 5 dl/g.

When the ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1)having an intrinsic viscosity within the above range is used, a rubbercomposition showing good fluidity (molding processability) and capableof providing a vulcanized rubber of excellent properties can beobtained.

The ethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) has anintrinsic viscosity [η], as measured in decalin at 135° C. of 0 1 to 5dl/g, preferably 0.2 to 2 dl/g, more preferably 0.3 to 1 dl/g.

By blending the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A2) having an intrinsic viscosity within the above range and theethylene-α-olefin-nonconjugated polyene copolymer rubber (A1), a rubbercomposition showing good fluidity (molding processability) and capableof providing a vulcanized rubber of excellent properties can beobtained.

The blend of the ethylene-α-olefin-nonconjugated polyene copolymerrubbers (A1) and (A2) has a Mooney viscosity [ML₁₊₄(100° C.)] of 5 to180, a molar ratio of ethylene to the α-olefin of 40/60 to 95/5(ethylene/α-olefin), and a polyene content of 0.5 to 50 in terms of aniodine value.

The ethylene-α-olefin-nonconjugated polyene copolymer rubbers (A), (A1)and (A2) can be prepared by processes described in, for example,Japanese Patent Publication No. 14497/1984. That is, theethylene-α-olefin-nonconjugated polyene copolymer rubbers (A), (A1) and(A2) can be obtained by copolymerizing ethylene, the α-olefin of 3 to 20carbon atoms and the nonconjugated polyene in the presence of Zieglercatalyst using hydrogen as a molecular weight modifier.

The ethylene-α-olefin-nonconjugated polyene copolymer rubbers (A), (A1)and (A2) may be graft-modified products obtained by graft-modifying theabove-described ethylene-α-olefin-nonconjugated polyene copolymerrubbers with unsaturated carboxylic acids or their derivatives (acidanhydrides, esters).

Examples of the unsaturated carboxylic acids include acrylic acid,methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconicacid, tetrahydrophthalic acid andbicyclo(2,2,1)hepto-2-ene-5,6-dicarboxylic acid.

Examples of the unsaturated carboxylic anhydrides include maleicanhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalicanhydride and bicyclo(2,2,1)hepto-2-ene-5,6-dicarboxylic anhydride.

Of these, preferred is maleic acid.

Examples of the unsaturated carboxylic esters include methyl acrylate,methyl methacrylate, dimethyl maleate, monomethyl maleate, dimethylfumarate, dimethyl itaconate, diethyl citraconate, dimethyltetrahydrophthalate and dimethylbi(cyclo(2,2,1)hepto-2-ene-5,6-dicarboxylate. Of these, preferred aremethyl acrylate and ethyl acrylate.

The graft modifiers (graft monomers) such as the unsaturated carboxylicacids are used singly or in combination of two or more kinds. In anycase, the graft quantity is preferably not more than 0.1 mol based on100 g of the aforementioned unmodified ethylene-α-olefin-nonconjugatedpolyene copolymer rubber.

When the ethylene-α-olefin-nonconjugated polyene copolymer rubbers (A),(A1) and (A2) having a graft quantity within the above range are used, arubber composition showing good fluidity (molding processability) andcapable of providing a vulcanized rubber molded product of excellentlow-temperature resistance can be obtained.

The graft-modified ethylene-α-olefin-nonconjugated polyene copolymerrubber can be obtained by causing the unmodifiedethylene-α-olefin-nonconjugated polyene copolymer rubber to react withthe unsaturated carboxylic acid or its derivative in the presence of aradical initiator.

This graft reaction can be carried out in a solution state or a moltenstate. When the graft reaction is performed in the molten state, it ismost efficient and preferred to continuously perform the reaction in anextruder.

Examples of the radical initiators used for the graft reaction include:

dialkyl peroxides, such as dicumyl peroxide, di-t-butyl peroxide,di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide,di-t-amyl peroxide, t-butyl hydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxyne)hexyne-3,2,5-dimethyl-2,5-di(benzoylperoxy)hexane,2,5-dimethyl-2,5-mono(t-butylperoxy)hexane andα,α′-bis(t-butylperoxy-m-isopropyl)benzene;

peroxy esters, such as t-butyl peroxyacetate, t-butyl peroxyisobutyrate,t-butyl peroxypivalate, t-butyl peroxymaleate, t-butylperoxyneodecanoate, t-butyl peroxybenzoate and di-t-butylperoxyphthalate;

ketone peroxides, such as dicylohexanone peroxide; and

mixtures of these compounds.

Of these, preferred are organic peroxides having a temperature, at whichthe half-life period thereof corresponds to one minute, of 130° to 200°C., and among them particularly preferred are dicumyl peroxide,di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane,t-butylcumyl peroxide, di-t-amyl peroxide and t-butyl hydroperoxide.

In the present invention, the ethylene-α-olefin-nonconjugated polyenecopolymer rubbers (A), (A1) and (A2) having a Mooney viscosity[ML₁₊₄(100° C.)] of 5 to 180, particularly 10 to 120, are preferablyused from the viewpoints of mechanical properties and fluidity moldingprocessability).

In the blend of the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A1) and the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A2), that is used as the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A), the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A1) is used in an amount of 30 to 95 parts by weight,preferably 35 to 80 parts by weight, more preferably 40 to 70 parts byweight, based on 100 parts by weight of the total amount of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A1) and theethylene-α-olefin-nonconjugated polyene copolymer rubber (A2); and theethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) is used inan amount of 5 to 70 parts by weight, preferably 10 to 65 parts byweight, more preferably 20 to 60 parts by weight, based on 100 parts byweight of the total amount of the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A1) and the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A2).

Organic peroxide (B)

The organic peroxide used in the invention is an organic peroxide whichis conventionally used for rubbers.

Examples of the organic peroxides include:

dialkyl peroxides, such as dicumyl peroxide, di-t-butyl peroxide,di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylcumyl peroxide,di-t-amyl peroxide, t-butyl hydroperoxide,2,5-dimethyl-2,5-di(t-butylperoxyne)hexyne-3,2,5-dimethyl-2,5-di(benzoylperoxy)hexane,2,5-dimethyl-2,5-mono(t-butylperoxy)hexane and 5,α,α′-bis(t-butylperoxy-m-isopropyl)benzene;

peroxy esters, such as t-butyl peroxyacetate, t-butyl peroxyisobutyrate,t-butyl peroxypivalate, t-butylperoxymaleic acid, t-butylperoxyneodecanoate, t-butyl peroxybenzoate and di-t-butylperoxyphthalate;

ketone peroxides, such as dicyclohexanone peroxide; and

mixtures of these compounds.

Of these, preferred are organic peroxides having a temperature, at whichthe half-life period thereof corresponds to one minute, of 130° to 200°C., and among them, particularly preferred are dicumyl peroxide,di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane,t-butylcumyl peroxide, di-t-amyl peroxide and t-butyl hydroperoxide.

The organic peroxide is used in an amount of 0.0003 to 0.05 mol,preferably 0.001 to 0.03 mol, based on 100 g of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), but it isdesired that the optimum amount is properly determined according therequired property values.

When the organic peroxide is used as a vulcanizing agent, avulcanization aid is preferably used in combination. Examples of thevulcanization aids include sulfur; quinonedioxime compounds, such asp-quinonedioxime; methacrylate compounds, such as polyethylene glycoldimethacrylate; allyl compounds, such as diallyl phthalate and triallylcyanurate; maleimide compounds; and divinyl benzene. The vulcanizationaid is used in an amount of 0.5 to 2 mol based on 1 mol of the organicperoxide, preferably in an equimolar amount.

Amine type anti-aging agent (C)

In the present invention, diphenylamines and/or phenylenediamines areused as the amine type anti-aging agent (C).

Examples of the diphenylamines includep-(p-toluenesulfonylamide)-diphenylamine,4,4′-(α,α′-dimethylbenzyl)diphenylamine, 4,4′-dioctyldiphenylamine, ahigh-temperature reaction product of diphenylamine and acetone, alow-temperature reaction product of diphenylamine and acetone, alow-temperature reaction product of diphenylamine, aniline and acetone,a reaction product of diphenylamine and diisobutylene, octylateddiphenylamine, dioctylated diphenylamine, p,p′-dioctyldiphenylamine andalkylated diphenyiamine.

Examples of the phenylenediamines include p-phenylenediamines, such asN,N′-diphenyl-p-phenylenediamine,n-isopropyl-N′-phenyl-p-phenylenediamine,N,N′-di-2-naphthyl-p-phenylenediamine,N-cyclohexyl-N′-phenyl-p-phenylenediamine,N-phenyl-N′-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine,N,N′-bis(1-methylheptyl)-p-phenylenediamine,N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine,N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine,N-bis(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,phenylhexyl-p-phenylenediamine and phenyloctyl-p-phenylenediamine.

Of these, particularly preferred are4,4′-(α,α′-dimethylbenzyl)diphenylamine andN,N′-di-2-naphthyl-p-phenylenediamine.

These compounds can be used singly or in combination of two or morekinds.

In the present invention, the amine type anti-aging agent (C) is used inan amount of 0.2 to 5 parts by weight, preferably 0.5 to 4 parts byweight, more preferably 1 to 3 parts by weight, based on 100 parts byweight of the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A). When the amine type anti-aging agent (C) is used in theabove-mentioned amount, the thermal aging resistance can be highlyimproved, and crosslinking of the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A) is not inhibited.

Hindered phenol type anti-aging agent (D)

Examples of the hindered phenol type anti-aging agents (D) include:

(1) 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenylbutane),

(2) 4,4′-butylidene-bis(3-methyl-6-t-butylphenol),

(3) 2,2-thiobis(4-methyl-6-t-butylphenol),

(4) 7-octadecyl-3-(4′-hydroxy-3′,5′-di-t-butylphenyl)propionate,

(5)tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane

(6)pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],

(7) triethyleneglycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate],

(8) 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],

(9)2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine,

(10) tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,

(11)2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate],

(12) N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxy)hydrocinnmamide,

(13) 2,4-bis[(octylthio) methyl]-o-cresol,

(14) 3,5-di-t-butyl-4-hydroxybenzyl-phosphonate-diethyl ester

(15) tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane,

(16) octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and

(17)3,9-bis[2-{3(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro[5,5]undecane.

Of these, preferred are the above phenol compounds (5) and (17).

In the present invention, the hindered phenol type anti-aging agent (D)is used in an amount of 0.2 to 5 parts by weight, preferably 0.5 to 4parts by weight, more preferably 1 to 3 parts by weight, based on 100parts by weight of the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A). When the hindered phenol type anti-aging agent (D) is usedin the above-mentioned amount, the thermal aging resistance can behighly improved, and crosslinking of the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A) is not inhibited.

Sulfur type anti-aging agent (E)

The sulfur type anti-aging agent (E) used in the invention is a sulfurtype anti-aging agent which is conventionally used for rubbers.

Examples of the sulfur type anti-aging agents (E) include those ofimidazole type, such as 2-mercaptobenzimidazole, zinc salt of2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole and zinc salt of2-mercaptomethylbenzimidazole; and those of aliphatic thioether type,such as dimyristyl thiodipropionate, dilauryl thiodipropionate,distearyl thiodipropionate and ditridecyl thiodipropionate,pentaerythritol-tetrakis-(β-lauryl-thiopropionate). Of these,particularly preferred are 2-mercagtobenzimidazole, zinc salt of2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of2-mercaptomethylbenzimidazole andpentaerythritol-tetrakis-(β-lauryl-thiopropionate).

In the present invention, the sulfur type anti-aging agent (E) is usedin an amount of 1 to 10 parts by weight, preferably 0.5 to 8 parts byweight, more preferably 1 to 6 parts by weight, based on 100 parts byweight of the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A). When the sulfur type anti-aging agent (E) is used in theabove-mentioned amount, the thermal aging resistance can be highlyimproved, and crosslinking of the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A) is not inhibited.

Other compounding ingredients

The heat-resistant rubber composition according to the invention can beused in an unvulcanized state, but when it is used in the form of avulcanized product such as a vulcanized rubber molded product or avulcanized rubber foamed product, its properties are most conspicuouslyexhibited.

To the heat-resistant rubber composition of the invention, knownadditives such as rubber reinforcement, softener, vulcanization aid,processing aid, foaming agent, foaming aid, colorant, dispersant andflame retardant can be added according to the use of the aimedvulcanized product, in addition to the ethylene-α-olefin-nonconjugatedpolyene copolymer rubber (A), the organic peroxide (B), if necessary,the amine type anti-aging agent (C) and/or the hindered phenol typeanti-aging agent (E), and the sulfur type anti-aging agent (E).

The total amount of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A), the amine type anti-aging agent (C), the hinderedphenol type anti-aging agent (D) and the sulfur type anti-aging agent(E) in the rubber composition is usually not less than 25% by weight,preferably not less than 40% by weight, though it varies depending onthe uses.

The rubber reinforcement serves to enhance mechanical properties such astensile strength, tear strength and abrasion resistance of thevulcanized rubber. Examples of the rubber reinforcements include carbonblack such as SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT and MT, carbonblack thereof which are surface-treated with, for example, silanecoupling agents, silica, activated calcium carbonate, powdery talc andpowdery silicic acid.

Though the amount of the rubber reinforcement can be selected accordingto the use of the vulcanized rubber, the amount thereof is usually notmore than 200 parts by weight, particularly not more than 100 parts byweight, based on 100 parts by weight of the total amount of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), the aminetype anti-aging agent (C), the hindered phenol type anti-aging agent (D)and the sulfur type anti-aging agent (E).

As the softeners, those conventionally used for rubbers are employable,and examples thereof include:

petroleum type softening agents, such as process oil, lubricating oil,paraffin, liquid paraffin, petroleum asphalt and vaseline;

coal tar type softeners, such as coal tar and coal tar pitch;

fatty oil type softeners, such as castor oil, linseed oil, rapeseed oiland coconut oil;

tall oil;

factice;

waxes, such as beeswax, carnauba wax and lanolin;

fatty acids and fatty acid salts, such as ricinolic acid, palmitic acid,barium stearate, calcium stearate and zinc laurate; and

synthetic polymer materials, such as petroleum resin, atacticpolypropylene and coumarone-indene resin.

Of these, preferred are petroleum type softeners, and among them,particularly preferred is process oil.

Though the amount of the softener can be selected according to the useof the vulcanized rubber, but the amount thereof is usually not morethan 200 parts by weight, particularly not more than 100 parts byweight, based on 100 parts by weight of the total amount of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), the aminetype anti-aging agent (C), the hindered phenol type anti-aging agent (D)and the sulfur type anti-aging agent (E).

When electron rays are used for the vulcanization instead of using thevulcanizing agent, the unvulcanized compounded rubber is irradiated withthe electron rays having energy of 0.1 to 10 MeV (megaelectron volt),preferably 0.3 to 2 MeV, in such a manner that the absorbed dose becomes0.5 to 35 Mrad (megarad), preferably 0.5 to 10 Mrad.

In this case, the vulcanization aid, that is used in combination withthe organic peroxide (vulcanizing agent), may be used. The vulcanizationaid is used in an amount of 0.0001 to 0.1 mol, preferably 0.001 to 0.03mol, based on 100 g of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A).

As the processing aids, those conventionally used for rubbers areemployable, and examples thereof include higher fatty acids, such asricinolic acid, stearic acid, palmitic acid and lauric acid; salts ofhigher fatty acids, such as barium stearate, zinc stearate and calciumstearate; and esters of higher fatty acids, such as recinolic acidester, stearic acid ester, palmitic acid ester and lauric acid ester.

The processing aid is used in an amount of not more than 10 parts byweight, preferably not more than 5 parts by weight, based on 100 partsby weight of the ethylene-α-olefin-nonconjugated polyene copolymerrubber (A), but it is desired that the optimum amount is properlydetermined according the required property values.

Examples of the foaming agents include:

inorganic foaming agents, such as sodium bicarbonate, sodium carbonate,ammonium bicarbonate, ammonium carbonate and ammonium nitrite;

nitroso compounds, such as N,N′-dimethyl-N,N′-dinitrosoterephthalamideand N,N′-dinitrosopentamethylenetetramine;

azo compounds, such as azodicarbonamide, azobisisobutyronitrile,azocyclohexylnitrile, azodiaminobenzene and barium azodicarboxylate;

sulfonylhydrazide compounds, such as benzenesulfonylhydrazide,toluenesulfonylhydrazide, p,p′-oxybis(benzenesulfonylhydrazide) anddiphenylsulfone-3,3′-disulfonylhydrazide; and

azide compounds, such as calcium azide, 4,4-diphenyldisulfonylazide andp-toluenesulfonylazide.

The foaming agent is used in an amount of 0.5 to 30 parts by weight,preferably 1 to 20 parts by weight, based on 100 parts by weight of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A). When thefoaming agent is used in the above-mentioned amount, a foamed producthaving an apparent specific gravity of 0.03 to 0.8 g/cm³ can beobtained. However, it is desired that the optimum amount is properlydetermined according the required property values.

A foaming aid may be used in combination with the foaming agent, ifdesired. The foaming aid has functions of lowering a decompositiontemperature of the foaming agent, acceleration of decomposition andproduction of uniform foam.

Examples of the foaming aids include organic acids, such as salicylicacid, phthalic acid, stearic acid and oxalic acid, urea and itsderivative.

The foaming aid is used in an amount of 0.01 to 10 parts by weight,preferably 0.1 to 5 parts by weight, based on 100 parts by weight of theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), but it isdesired that the optimum amount is properly determined according therequired property values.

Preparation of rubber composition

As described hereinbefore, the heat-resistant rubber composition of theinvention can be used in the unvulcanized state, but when it is used inthe form of a vulcanized product such as a vulcanized rubber moldedproduct or a vulcanized rubber foamed product, its properties are mostconspicuously exhibited.

For preparing a vulcanizate from the heat-resistant rubber compositionof the invention, an unvulcanized compounded rubber is first prepared,then the compounded rubber is molded into a product of desired shape,and the product is vulcanized, similarly to a method of vulcanizingconventional rubbers.

For the vulcanization, any of a heating method using a vulcanizing agentand an electron ray-irradiation method may be adopted.

The heat-resistant rubber composition of the invention can be preparedby, for example, the following process.

That is, the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A), and if necessary, additives such as filler and softener are kneadedat 80° to 170° C. for 3 to 10 minutes using internal mixers (closed typemixers) such as Banbury mixer, kneader and intermixer; then the organicperoxide (vulcanizing agent), and if necessary, the vulcanization aidand the foaming agent are added; and the resulting mixture is kneaded ata roll temperature of 40° to 80° C. for 5 to 30 minutes using rolls(e.g., open rolls) or kneaders, followed by rolling.

The heat-resistant rubber composition of the invention comprising theanti-aging agent can be prepared by kneading theethylene-α-olefin-nonconjugated polyene copolymer rubber (A), the aminetype anti-aging agent (C), the hindered phenol type anti-aging agent(D), the sulfur type anti-aging agent (E), and if necessary, additivessuch as filler and softener at 80° to 170° C. for 3 to 10 minutes usinginternal mixers (closed type mixers) such as Banbury mixer, kneader orintermixer; then adding the organic peroxide (B) (vulcanizing agent),and if necessary, the vulcanization aid and the foaming agent; andkneading the resulting mixture at a roll temperature of 40° to 80° C.for 5 to 30 minutes using rolls (e.g., open rolls) or kneaders, followedby rolling.

If the kneading temperature of the internal mixer is low, the anti-agingagents (C), (D) and (E), the vulcanizing agent, and other additives suchas colorant, dispersant, flame retardant and foaming agent may bekneaded together with the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A) and additives such as filler and softener.

The vulcanizable heat-resistant rubber composition of the inventionobtained as above is molded into a desired shape using various meanssuch as an extrusion molding machine, a calender roll, a press, aninjection molding machine or a transfer molding machine, andsimultaneously or thereafter the molded product is heated at atemperature of 120° to 270° C. for 1 to 30 minutes in a vulcanizing bathto perform vulcanization. Or, the vulcanized product can be obtained byirradiation to it with electron rays in the aforesaid manner. In thevulcanization, a mold may be used or may not be used. When a mold is notused, the vulcanization is generally carried out continuously. Theheating in the vulcanizing bath can be performed by the use of heatingmeans such as hot air, glass bead fluidized bed, UHF (ultrahighfrequency electromagnetic wave), steam or LCM (molten salt bath). In thevulcanization using irradiation with electron rays, a compounded rubbercontaining no vulcanizing agent is used.

EFFECT OF THE INVENTION

A heat-resistant rubber composition of the invention comprises thespecific ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)and the organic peroxide (B). Therefore, the composition has highcrosslinking efficiency and a high modulus, and can provide a vulcanizedrubber molded product having excellent resistance to environmentaldeterioration such as thermal aging resistance.

The other heat-resistant rubber composition of the invention comprisesthe specific ethylene-α-olefin-nonconjugated polyene copolymer rubber(A), the amine type anti-aging agent (C) and/or the hindered phenol typeanti-aging agent (E), the sulfur type anti-aging agent (E) and theorganic peroxide (B). Therefore, the composition can provide avulcanized rubber molded product showing not only excellent mechanicaland electrical properties but also prominently high thermal agingresistance. These effects can be obtained by the use of a combination ofthe amine type anti-aging agent (C) and the sulfur type anti-aging agent(E), a combination of the hindered phenol type anti-aging agent (D) andthe sulfur type anti-aging agent (E), or a combination of the amine typeanti-aging agent (C), the hindered phenol type anti-aging agent (D) andthe sulfur type anti-aging agent (E).

Among the heat-resistant composition of the invention, a compositioncomprising ethylene-α-olefin-nonconjugated polyene copolymer rubber (A)containing a blend of specific amounts of theethylene-α-olefin-nonconjugated polyene copolymer rubbers (A1) and (A2)having different intrinsic viscosities (i.e., having different molecularweights) particularly has extremely good fluidity (moldingprocessability) and can provide a vulcanized rubber molded productshowing not only excellent mechanical and electrical properties but alsoprominently high thermal aging resistance.

Accordingly, the heat-resistant rubber composition which exerts sucheffects as mentioned above can be favorably used for automotive partssuch as weatherstrip, door glass run channel, window frame, radiatorhose, brake parts and wiper blade; industrial rubber parts such asrubber roll, belt, packing and hose; electrical insulating materialssuch as anode cap and grommet; and building materials such as buildinggasket.

EXAMPLE

The present invention will be further described with reference to thefollowing examples, but it should be construed that the invention is inno way limited to those examples.

Example 1

At first, the ingredients shown in Table 1 were kneaded at 140°-150° C.for 5 minutes using a 1.7 liter Banbury mixer to prepare a blend (1).

TABLE 1 Amounts (Parts by Ingredient weight) EPT rubber (A component) *1100 Zinc white *2 5 Stearic acid *3 1 HAF carbon black *4 50 Softener *510 Activator *6 1 Hindered phenol anti-aging agent *7 2 Sulfuranti-aging agent *8 4 *1 Ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) having a molar ratio of ethylene to propylene(ethylene/propylene by mol): 68/32; an intrinsic viscosity [η], asmeasured in decalin at 135° C.: 2.2 dl/g; and an iodine value: 3. *2:available from Sakai Chemical Industry Co., Ltd. *3: Tsubaki (TradeMark) available from NOF Corporation *4: Asahi #70 (Trade Mark)available from Asahi Carbon, Ltd. *5: Diana Process oil PW 380 (TradeMark) available from Idemitu Kosan, Co., Ltd. *6: Polyethylene glycol,Molecular weight = 4000 *7: Irganox 1010 (Trade Mark), available fromCiba Geigy, Ltd. *8: NOCRAC MB (Trade Mark), Ouchi-Shinko ChemicalIndustry Co., Ltd.

Next, a rubber composition containing the resulting blend (HA1) waswound around 8 inch open rolls (a product of NIHON ROLL K.K.). To thecomposition on the open roll, the ingredients shown in Table 2 wereadded in accordance with the formulation as shown in Table 2 and kneadedfor 3 minutes, followed by sheeting to prepare a sheet of a blend (HA2)having a thickness of 3 mm. In this operation, the surface temperatureof the front roll was 50° C. and that of the back roll was 60° C.

TABLE 2 Amount (Parts by Ingredient weight) Blend (HA2) 173 Organicperoxide (B component) *9 7.0 Cross-linking assistant *10 4.0 *9: MitsuiDCO-40C (Trade Mark), available from Mitsui Pertrochemical Industries,Ltd. Dicumyl peroxide (concentration 40%) *10: TAIC (Trade Mark)available from Nibon Kasei, Ltd.

The resulting blend was heated at a molding temperature 170° C. for 20minutes by means of a press molding apparatus (a product of KOHTAKISEIKI K.K.) to prepare a vulcanized rubber sheet having a thickness of 2mm. The resulting sheet was evaluated in modulus, tensile properties,cross-linking density and aging properties.

The methods for measuring these properties are as described below.

(1) Modulus

Tensile test in accordance with JIS K 6301 was carried out at ameasuring temperature of 25° C. at a pulling rate of 500 mm/min. and themodulus M200 at 200% elongation was measured.

(2) Tensile Properties

Tensile test in accordance with JIS K 6301 was carried out at ameasuring temperature of 25° C. at a pulling rate of 500 mm/min., andelongation (E_(B)) and strength (T_(B)) at rupture of the vulcanizedsheet were measured.

(3) Effective Network Chain Density (an index of crosslinking density)

In accordance with JIS K 6301, the vulcanized sheet was immersed intoluene at 37° C. and the effective network chain density was calculatedby the following formula.

ν(cc⁻¹)=(ν_(R)+ln(1−ν_(R))+μν_(R) ²)/(−V₀(ν_(R) ^(⅓)−ν_(R)/2)

ν_(R): Volume ratio of a pure rubber to the volume of the swelled purerubber in the swelled vulcanized rubber (i.e., to the volume of purerubber+absorbed solvent).

μ: Rubber-solvent interaction coefficient (using data disclosed in JSRHANDBOOK published by Japan Synthetic Rubber Co.)

V₀: Molar volume of solvent

ν(cc⁻¹): Effective network chain concentration. The number of effectivenetwork chains in 1 cc of the pure rubber

(4) Aging properties

In accordance with JIS K 6301, the vulcanized sheet was allowed to agein an oven at 175° C. for 168 hours. Then, the sheet was subjected tothe tensile test at a measuring temperature of 25° C. at a pulling rateof 500 m/min. to measure elongation (E_(B)) and strength (T_(B)) atrupture of the vulcanized sheet. From the measurements, a tensilestrength retention ratio A_(R)(T_(B)) and an elongation retention ratioA_(R)(E_(B)) were calculated.

The results are set forth in Table 3.

Example 2

Example 1 was repeated except that Kayacumyl AD-40 (trade name)available from KAYAKUAKZO Co. was used as the organic peroxide (B).

The results are set forth in Table 3.

Example 3

Example 1 was repeated except that theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (2) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (2):

Ethylene/propylene (by mol): 68/32

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.6 dl/g

Iodide value=3

The results are set forth in Table 3.

Example 4

Example 1 was repeated except that theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (3) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (3):

Ethylene/propylene (by mol): 74/26

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=5

The results are set forth in Table 3.

Example 5

Example 1 was repeated except that theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (4) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (4):

Ethylene/propylene (by mol): 58/42

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=4

The results are set forth in Table 3.

Example 6

Example 1 was repeated except that theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (5) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (5):

Ethylene/propylene (by mol): 74/26

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=10

The results are set forth in Table 3.

Example 7

Example 1 was repeated except that theethylene-1-butene-5-vinyl-2-norbornene copolymer rubber (6) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-1-butene-5-vinyl-2-norbornene copolymer rubber (6):

Ethylene/1-butene (by mol): 80/20

Intrinsic viscosity [η] measured in decalin at 135° C.: 3.0 dl/g

Iodide value=5

The results are set forth in Table 3.

Comparative Example 1

Example 1 was repeated except that the ethylene-propylene copolymerrubber (7) described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene copolymer rubber (7):

Ethylene/propylene (by mol): 58/42

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.4 dl/g

iodide value=0

The results are set forth in Table 3.

Comparative Example 2

Example 1 was repeated except that the ethylene-propylene copolymerrubber (8) described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene copolymer rubber (8):

Ethylene/propylene (by mol): 70/30

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.4 dl/g

25 Iodide value=0

The results are set forth in Table 3.

Comparative Example 3

Example 6 was repeated except that 1.5 phr of sulfer, and 0.5 phr ofNocceller M (trade name, available from Ouchi-Shinko Chemical industryCo., Ltd.) and 1.0 phr of Nocceller TT (trade name, available fromOuchi-Shinko Chemical Industry Co., Ltd.) as the vulcanizingaccelerators were used in place of the organic peroxide and thecrosslinking assistant in Example 6.

The results are set forth in Table 3.

Comparative Example 4

Example 1 was repeated except that theethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (9)described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (9):

Ethylene/propylene (by mol): 68/32

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=6

The results are set forth in Table 3.

Comparative Example 5

Example 1 was repeated except that theethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (10)described below was used in place of theethylene-propylene-5-vinylidene-2-norbornene copolymer rubber (1) inExample 1.

Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (10):

Ethylene/propylene (by mol): 66/34

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=13

The results are set forth in Table 3.

Comparative Example 6

Example 1 was repeated except that theethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (11)described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (11):

Ethylene/propylene (by mol): 66/34

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=22

The results are set forth in Table 3.

Comparative Example 7

Example 1 was repeated except that theethylene-propylene-dicyclopentadiene copolymer rubber (12) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-dicyclopentadiene copolymer rubber (12):

Ethylene/propylene (by mol): 68/32

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=6

The results are set forth in Table 3.

Comparative Example 8

Example 1 was repeated except that theethylene-propylene-dicyclopentadiene copolymer rubber (13) describedbelow was used in place of the ethylene-propylene-5-vinyl-2-norbornenecopolymer rubber (1) in Example 1.

Ethylene-propylene-dicyclopentadiene copolymer rubber (13):

Ethylene/propylene (by mol): 66/34

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=10

The results are set forth in Table 3.

Comparative Example 9

Example 1 was repeated except that the ethylene-propylene-1,4-hexadienecopolymer rubber (14) described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene-1,4-hexadiene copolymer rubber (14):

Ethylene/propylene (by mol): 66/34

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=6

The results are set forth in Table 3.

Comparative Example 10

Example 1 was repeated except that the ethylene-propylene-1,4-hexadienecopolymer rubber (15) described below was used in place of theethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example1.

Ethylene-propylene-1,4-hexadiene copolymer rubber (15):

Ethylene/propylene (by mol): 66/34

Intrinsic viscosity [η] measured in decalin at 135° C.: 2.2 dl/g

Iodide value=15

The results are set forth in Table 3.

TABLE 3 Example 1 2 3 4 5 Composition [parts by weight] Copolymer rubberEthylene-propylene-VNB c.r. (1) 100 100 — — — Ethylene-propylene-VNBc.r. (2) — — 100 — — Ethylene-propylene-VNB c.r. (3) — — — 100 —Ethylene-propylene-VNB c.r. (4) — — — — 100 Ethylene-propylene-VNB c.r.(5) — — — — — Ethylene-propylene-VNB c.r. (6) — — — — —Ethylene-propylene c.r. (7) — — — — — Ethylene-propylene c.r. (8) — — —— — Hindered phenol anti-aging agent (D) 2 2 2 2 2 Igranox 1010 (TradeMark) Sulfur anti-aging agent (E) 4 4 4 4 4 NOCRAC MB (Trade Mark)Dicumyl peroxide Concentration 40% Mitsui DCP-40C (Trade Mark) 7 — 7 7 7Kyakumill AS-40C (Trade Mark) — 7 — — — Cross-linking assistant 4 4 4 44 Sulfur — — — — — Vulcanizing accelerator Noceller M (Trade Mark) — — —— — Noceller TT (Trade Mark) — — — — — Vulcanized rubber Original stateEffective network chain 10.8 10.2 11.8 12.5 10.1 concentration [× 10¹⁹cc⁻¹] M₂₀₀ [MPa] 7.5 7.2 8.1 8.9 7.3 Thermal aging resistance 175° C. ×168 hrs. Tensile strength retention ratio 85 81 86 75 70 A_(R) (T_(B))[%] Elongation retention ratio 80 74 82 74 72 A_(R) (E_(B)) [%] ExampleComp. Example 6 7 1 2 3 Composition [parts by weight] Copolymer rubberEthylene-propylene-VNB c.r. (1) — — — — — Ethylene-propylene-VNB c.r.(2) — — — — — Ethylene-propylene-VNB c.r. (3) — — — — —Ethylene-propylene-VNB c.r. (4) — — — — — Ethylene-propylene-VNB c.r.(5) 100 — — — 100 Ethylene-propylene-VNB c.r. (6) — 100 — — —Ethylene-propylene c.r. (7) — — 100 — — Ethylene-propylene c.r. (8) — —— 100 — Hindered phenol anti-aging agent (D) 2 2 2 2 2 Igranox 1010(Trade Mark) Sulfur anti-aging agent (E) 4 4 4 4 4 NOCRAC MB (TradeMark) Dicumyl peroxide Concentration 40% Mitsui DCP-40C (Trade Mark) 7 77 7 — Kyakumill AS-40C (Trade Mark) — — — — — Cross-linking assistant 44 4 4 — Sulfur — — — — 1.5 Vulcanizing accelerator Noceller M (TradeMark) — — — — 0.5 Noceller TT (Trade Mark) — — — — 1.0 Vulcanized rubberOriginal state Effective network chain 16.5 13.5 4.7 5.1 5.2concentration [× 10¹⁹ cc⁻¹] M₂₀₀ [MPa] 13.5 12.1 3.9 4.5 4.1 Thermalaging resistance 175° C. × 168 hrs. Tensile strength retention ratio 7283 63 70 4 A_(R) (T_(B)) [%] Elongation retention ratio 70 82 80 84 2A_(R) (E_(B)) [%] Comp. Example 4 5 6 7 Composition [parts by weight]Copolymer rubber Ethylene-propylene-ENB c.r. (9) 100 — — —Ethylene-propylene-ENB c.r. (10) — 100 — — Ethylene-propylene-ENB c.r.(11) — — 100 — Ethylene-propylene-DCPD c.r. (12) — — — 100Ethylene-propylene-DCPD c.r. (13) — — — — Ethylene-propylene-1,4HD c.r.(14) — — — — Ethylene-propylene-1,4HD c.r. (15) — — — — Hindered phenolanti-aging agent (D) 2 2 2 2 Igranox 1010 (Trade Mark) Sulfur anti-agingagent (E) 4 4 4 4 NOCRAC MB (Trade Mark) Dicumyl peroxide 7 7 7 7Concentration 40% Mitsui DCP-40C (Trade Mark) Cross-linking assistant 44 4 4 Vulcanizing rubber Original state Effective network chain 7.8 9.811.5 7.9 concentration [× 10¹⁹ cc⁻¹] M₂₀₀ [MPa] 5.1 6.1 9.5 5.3 Heataging resistance 175° C. × 168 hrs. Tensile strength retention ratio 6448 31 50 A_(R) (T_(B)) [%] Elongation retention ratio 57 30 20 48 A_(R)(E_(B)) [%] Comp. Example 8 9 10 Composition [parts by weight] Copolymerrubber Ethylene-propylene-ENB c.r. (9) — — — Ethylene-propylene-ENB c.r.(10) — — — Ethylene-propylene-ENB c.r. (11) — — —Ethylene-propylene-DCPD c.r. (12) — — — Ethylene-propylene-DCPD c.r.(13) 100 — — Ethylene-propylene-1,4HD c.r. (14) — 100 —Ethylene-propylene-1,4HD c.r. (15) — — 100 Hindered phenol anti-agingagent (D) 2 2 2 Igranox 1010 (Trade Mark) Sulfur anti-aging agent (E) 44 4 NOCRAC MB (Trade Mark) Dicumyl peroxide 7 7 7 Concentration 40%Mitsui DCP-40C (Trade Mark) Cross-linking assistant 4 4 4 Vulcanizingrubber Original state Effective network chain 10.2 6.5 6.9 concentration[× 10¹⁹ cc⁻¹] M₂₀₀ [MPa] 7.4 4.6 5.0 Thermal aging resistance 175° C. ×168 hrs. Tensile strength retention ratio 40 70 64 A_(R) (T_(B)) [%]Elongation retention ratio 24 62 57 A_(R) (E_(B)) [%] VNB:5-vinyl-2-norbornene ENB: 5-ethylene-2-norbonene, DCPD:dicylcopentadiene, 1,4HD: 1,4-hexadiene

Described below are components used in the following examples 8-18 andcomparative examples 11-25.

[1] Components used in Examples 8-14 and Comparative Examples 11-20

Ethylene-α-olefin-nonconjugated polyene copolymer rubber

(A-1): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 2.2 dl/g

(A-2): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 15

Intrinsic viscosity [η]: 2.2 dl/g

(A-3): Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 2.2 dl/g

(A-4): Ethylene-propylene-dicyclopentadiene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 2.2 dl/g

(A-5): Ethylene-propylene-1,4-hexadiene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 2.2 dl/g

(A-6): Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 22

Intrinsic viscosity [η]: 1.9 dl/g

(A-7): Ethylene-propylene copolymer rubber

Ethylene/propylene (by mol): 58/42

Iodine value: 0

Intrinsic viscosity [η]: 2.4 dl/g

Amine type anti-aging agent (C)

(C-1): N,N′-Di-2-naphthyl-p-phenylenediamine

(C-2): N,N′-Diphenyl-p-phenylenediamine

(C-3): 4,4′-(α,α-dimethylbenzyl)diphenylamine

Hindered phenol type anti-aging agent (D)

(D-1):3,9-Bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro[5,5]undecane

Sulfur type anti-aging agent (E)

(E-1): Pentaerythritol-tetrakis-(β-lauryl-thiopropionate)

Phosphite type anti-aging agent

(F-1): 4,4′-Butylidenebis(3-methyl-6-t-di-tridecylphosphite)

[2] Components used in Examples 15-18 and Comparative Examples 21-25

Copolymer rubber (A1)

(A1-1): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 3.7 dl/g

(A1-2): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 3.5 dl/g

(A1-3): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 4.0 dl/g

(A1-4): Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 3.7 dl/g

(A1-5): Ethylene-propylene-dicyclopentadiene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 3.7 dl/g

(A1-6): Ethylene-propylene copolymer rubber

Ethylene/propylene (by mol): 80/20

Iodine value: 0

Intrinsic viscosity [η]: 3.7 dl/g

(A1-7): Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 6

Intrinsic viscosity [η]: 2.2 dl/g

Copolymer rubber

(A2-1): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 0.6 dl/g

(A2-2): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 0.5 dl/g

(A2-3): Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 68/32

Iodine value: 3

Intrinsic viscosity [η]: 0.3 dl/g

(A2-4): Ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 0.6 dl/g

(A2-5): Ethylene-propylene-dicyclopentadiene copolymer rubber

Ethylene/propylene (by mol): 78/22

Iodine value: 3

Intrinsic viscosity [η]: 0.6 dl/g

(A2-6): Ethylene-propylene copolymer rubber

Ethylene/propylene (by mol): 80/20

Iodine value: 0

Intrinsic viscosity [η]: 0.5 dl/g

Amine type anti-aging agent (C)

(C-1): N,N ′-di-2-naphthyl-p-phenylenediamine

Hindered phenol type anti-agent agent (D).

(D-1):3,9-Bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro[5,5]undecane

Sulfur type anti-aging agent (E)

(E-1): Pentaerythritol-tetrakis-(β-lauryl-thiopropionate)

Phosphite type anti-aging agent

(F-1): 4,4′-Butylidenebis(3-methyl-6-t-di-tridecylphosphite)

Properties of the vulcanized rubbers obtained in the following exampleswere measured in accordance with the methods described below.

[1] Property tests of vulcanized rubbers obtained in Examples 8-14 andComparative Examples 10-20

Test items

tensile test, aging test

Test methods

The tensile test and the aging test were carried out in accordance withJIS K 6301. That is, tensile strength (T_(B)) and elongation (E_(B))were measured in the tensile test.

As the aging test, an air-oven aging test was carried out at 120° C. for70 hours. In this test, retention ratios of the properties to thosebefore aging, i.e., a tensile strength retention ratio A_(R)(T_(B)), anelongation retention ratio A_(R)(E_(B)) and a retention ratio of tensilestrength×elongation A_(R)(T_(B)×E_(B)), were measured.

[2] Property tests of vulcanized rubbers obtained in Examples 15-18 andComparative Examples 21-25

(1) Property in original state

tensile strength (T_(B)), elongation (E_(B))

(2) Thermal aging resistance (190° C.×168 hrs)

tensile strength retention ratio [A_(R)(T_(B))]

elongation retention ratio [A_(R)(E_(B))]

retention ratio of tensile strength×elongation [A_(R)(T_(B)×E_(B))]

Molding processability

(a) Roll processability

The kneadate obtained in each example was allowed to stand at roomtemperature for 24 hours. The kneadate of 1.5 kg was wound around 8-inchopen rolls at each roll temperature of 50° C. keeping a gap of 5 mmbetween rolls. The state of the kneadate wound around the rolls wasobserved and evaluated by the following five ranks.

Five-rank evaluation

5: The rubber band perfectly adheres to the roll, and the bank smoothlyrotates.

4: Rubber band sometimes separates from the roll surface between the topof the roll and the bank.

3: Rubber band separates from the roll surface between the top of theroll and the bank.

2: Rubber band does not adhere to the roll surface, and the rollprocessing is impossible unless the band is supported by hand.

1: Rubber band does not adhere at all to the roll surface and hangsdown. The roll processing is impossible unless the band is supported byhand.

(b) Extrusion processability

The kneadate obtained in each example was allowed to stand at roomtemperature for 24 hours. The kneadate was extruded by a 50 mm extruderunder the below-described conditions. The surface of the extrudedproduct was evaluated by the following five ranks as an indication ofthe extrusion processability.

Extrusion conditions

Extruder: 50 mm extruder having L/D of 14 and equipped with a modifiedGarvey die

Extrusion temperature: back of cylinder/front of cylinder/head=60°C./70° C./80° C.

Five-rank evaluation

5: No protrusions and depressions are observed on the surface, and thegloss is excellent.

4: Protrusions and depressions are rarely observed on the surface, andthe gloss is bad.

3: Protrusions and depressions are slightly observed, and the gloss isbad.

2: Protrusions and depressions are observed on the surface, and thegloss is bad.

1: Conspicuous protrusions and depressions are observed on the surface,and the gloss is very bad.

Examples 8-14, Comparative examples 10-20

Rubber compounding ingredients common to Examples 8 to 14 andComparative Examples 10 to 20 and the amounts thereof are set forth inTable 4.

TABLE 4 Amount Ingredient (parts by weight) Copolymer rubber 100 Softsilica *1 30 Talc *2 30 Paraffinic oil *3 10 Zinc white 5 Stearic acid 2Organic peroxide *4 6.8 *1: Aerosil (trade name, available from NipponSilica Industrial Co., Ltd.) *2: Hightoron (trade name, available fromTakehara Chemical Industrial Corporation) *3: Diana Process Oil PW-380(trade name, available from Idemitsu Kosan Co., Ltd.) *4: a product of40% by weight of dicumyl peroxide

The rubber compounding ingredients shown in Table 4 and othercompounding ingredients shown in Table 5 were used in the amounts shownin Table 4 and Table 5, to prepare a rubber composition.

In the preparation, the ingredients other than the organic peroxide werekneaded at 140° to 150° C. for 5 minutes using a 1.7 liter Banburymixer. Then, the resulting kneadate and the organic peroxide werekneaded at 50° to 60° C. for 5 minutes using an 8 inch open roll.

The resulting kneadate was subjected to press vulcanization at 170° C.for 10 minutes to prepare a vulcanized rubber sheet having a thicknessof 2 mm, from which specimens for the above tests were prepared.

TABLE 5 Example 8 9 10 11 Composition [parts by weight] Copolymer rubberEthylene-propylene-VNB c.r. (A-1) 100 100 100 — Ethylene-propylene-VNBc.r. (A-2) — — — 100 Ethylene-propylene-ENB c.r. (A-3) — — — —Ethylene-propylene-DCPD c.r. (A-4) — — — — Ethylene-propylene-1,4HD c.r.(A-5) — — — — Ethylene-propylene-ENB c.r. (A-6) — — — —Ethylene-propylene c.r. (A-7) — — — — Amine anti-aging agent (C)N,N′-di-2-naphthyl-p- 1 — — — phenylenediamine (C-1)N,N′-diphenyl-p-phenylenediamine — 1 — — (C-2) Hindered phenolanti-aging agent (D) — — 1 1 3,9-bis [2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl) propinonyloxy}-1,1-dimethylethyl]-2,4-8,10-tetraoxaspiro [5,5]undecane (D-1) Sulfur anti-aging agent (E) 44 4 4 Pentaerythritol-tetrakis-(β- lauryl-thiopropionate) (E-1)Vulcanized rubber Original state tensile strength T_(B) [kgf/cm²] 108102 115 105 elongation E_(B) [%] 540 530 520 500 Thermal agingresistance 175° C. × 168 hrs. Tensile strength retention ratio 69 65 7260 A_(R) (T_(B)) [%] Elongation retention ratio A_(R) (E_(B)) [%] 75 7470 74 A_(R) (T_(B) × E_(B)) [%] 52 48 51 42 Comp. Example 11 12 13 14 1516 Composition [parts by weight] Copolymer rubber Ethylene-propylene-VNBc.r. — — — 100 — — (A-1) Ethylene-propylene-VNB c.r. — — — — — — (A-2)Ethylene-propylene-ENB c.r. 100 — — — — — (A-3) Ethylene-propylene-DCPD— — — — 100 — c.r. (A-4) Ethylene-propylene-1,4HD — — — — — 100 c.r.(A-5) Ethylene-propylene-ENB c.r. — 100 — — — — (A-6) Ethylene-propylenec.r. — — 100 — — — (A-7) Amine anti-aging agent (C)N,N′-di-2-naphthyl-p- 1 1 1 2 1 1 phenylenediamine (C-1)N,N′-diphenyl-p-phenylene- — — — — — — diamine (C-2) Hindered phenolanti-aging — 1 1 2 — — agent (D) 3,9-bis [2-{3-(3-t-butyl-4-hydroxy-5-methyl- phenyl) propinonyloxy}-1,1-dimethyl-ethyl]-2,4-8,10-tetraoxaspiro [5,5]undecane (D-1) Sulfur anti-agingagent (E) 4 4 4 — 4 4 Pentaerythritol-tetrakis-(β-lauryl-thiopropionate) (E-1) Vulcanized rubber Original state tensilestrength T_(B) [kgf/cm²] 104 112 96 106 103 105 elongation E_(B) [%] 650490 680 520 630 650 Thermal aging resistance 175° C. × 168 hrs. Tensilestrength retention ratio 46 48 32 28 24 18 A_(R) (T_(B)) [%] Elongationretention ratio A_(R) (E_(B)) [%] 40 42 70 30 18 40 A_(R) (T_(B) ×E_(B)) [%] 18 20 22 8 4 8 Example 12 13 14 Composition (parts by weight)Copolymer rubber Ethylene-propylene-VNB c.r. (A-1) 100 100 100Ethylene-propylene-ENB c.r. (A-3) — — — Ethylene-propylene-ENB c.r.(A-6) — — — Ethylene-propylene c.r. (A-7) — — — Amine anti-aging agent(C) N,N′-di-2-naphthyl-p- 1 — — phenylenediamine (C-1)N,N′-diphenyl-p-phenylenediamine — 1 — (C-2 4,4′-(α,α-dimethylbenzyl) —— 1 diphenylamine (C-3) Hindered phenol anti-aging agent (D) 1 1 13,9-bis [2-{3-(3-t-butyl-4- hydroxy-5-methylphenyl)propinonyloxy}-1,1-dimethylethyl]- 2,4-8,10-tetraoxaspiro [5,5]undecane(D-1) Sulfur anti-aging agent (E) 4 4 4 Pentaerythritol-tetrakis-(β-lauryl-thiopropionate) (E-1) Phosphine anti-aging agent — — —4,4′-butylidenebis(3-methyl-6-t- buthyl-di-tridecylphosphite) (F-1)Vulcanized rubber Original state tensile strength T_(B) [kgf/cm²] 108102 115 elongation E_(B) [%] 540 530 520 Heat aging resistance 175° C. ×168 hrs. Tensile strength retention ratio 69 65 72 A_(R) (T_(B)) [%]Elongation retention ratio A_(R) (E_(B)) [%] 75 74 70 A_(R) (T_(B) ×E_(B)) [%] 52 48 51 Comp. Ex. 17 18 19 20 Composition (parts by weight)Copolymer rubber Ethylene-propylene-VNB c.r. (A-1) — — — 100Ethylene-propylene-ENB c.r. (A-3) — — 100 — Ethylene-propylene-ENB c.r.(A-6) 100 — — — Ethylene-propylene c.r. (A-7) — 100 — — Amine anti-agingagent (C) N,N′-di-2-naphthyl-p- 1 1 1 1 phenylenediamine (C-1)N,N′-diphenyl-p-phenylenediamine — — — — (C-2 4,4′-(α,α-dimethylbenzyl)— — — — diphenylamine (C-3) Hindered phenol anti-aging agent (D) 1 1 — 13,9-bis [2-{3-(3-t-butyl-4- hydroxy-5-methylphenyl)propinonyloxy}-1,1-dimethylethyl]- 2,4-8,10-tetraoxaspiro [5,5]undecane(D-1) Sulfur anti-aging agent (E) 4 4 4 — Pentaerythritol-tetrakis-(β-lauryl-thiopropionate) (E-1) Phosphine anti-aging agent — — — 44,4′-butylidenebis(3-methyl-6-t- buthyl-di-tridecylphosphite) (F-1)Vulcanized rubber Original state tensile strength T_(B) [kgf/cm²] 112 9694 98 elongation E_(B) [%] 490 590 610 600 Heat aging resistance 175° C.× 168 hrs. Tensile strength retention ratio 48 32 24 18 A_(R) (T_(B))[%] Elongation retention ratio A_(R) (E_(B)) [%] 42 70 35 20 A_(R)(T_(B) × E_(B)) [%] 20 22 8 4 VNB: 5-vinyl-2-norbornene, ENB:5-ethylidene-2-norbornene DCPD: dicylopentadiene, 1,4HD: 1,4-hexadine

Examples 15-18 Comparative examples 21-25

Rubber compounding ingredients common to Examples 15 to 18 andComparative Examples 21 to 25 and the amounts thereof are set forth inTable 6.

TABLE 6 Amount Ingredient (parts by weight) Copolymer rubber (A1) and/or100 Copolymer rubber (A2) Soft silica *1 30 Talc *2 30 Paraffinic oil *310 Zinc white 5 Stearic acid 2 Organic peroxide *4 6.8 *1: Aerosil(trade name, available from Nippon Silica Industrial Co., Ltd.) *2:Hightoron (trade name, available from Takehara Chemical IndustrialCorporation) *3: Diana Process Oil PW-380 (trade name, available fromIdemitsu Kosan Co., Ltd.) *4: a product of 40% by weight of dicumylperoxide

The rubber compounding ingredients shown in Table 6 and othercompounding ingredients shown in Table 7 were used in the amounts shownin Table 6 and Table 7, to prepare a rubber composition.

In the preparation, the ingredients other than the organic peroxide werekneaded at 140° to 150° C. for 5 minutes using a 1.7 liter Banburymixer. Then, the resulting kneadate and the organic peroxide werekneaded at 50° to 60° C. for 5 minutes using an 8 inch open roll.

The resulting kneadate was subjected to press vulcanization at 170° C.for 10 minutes to prepare a vulcanized rubber sheet having a thicknessof 2 mm, from which specimens for the above tests were prepared.

The resulting specimens were subjected to the above test.

The results are set forth in Table 7.

TABLE 7 Example Comp. Ex. 15 16 17 21 22 Composition (parts by weight)Copolymer rubber (A-1) (A1-1) 50 — — — — (A1-2) — 70 — — — (A1-3) — — 70— — (A1-4) — — — 50 — (A1-5) — — — — 50 Copolymer rubber (A2) (A2-1) 50— — — — (A2-2) — 30 — — — (A2-3) — — 30 — — (A2-4) — — — 50 — (A2-5) — —— — 50 Amine anti-aging agent (C) 1 1 1 1 1 (C-1) Hindered phenol anti-1 1 1 1 1 aging agent (D) (D-1) Sulphur anti-aging agent (E) 4 4 4 4 4(E-1) Vulcanized rubber Original state Tensile strength 118 108 104 113108 T_(B) (kgf/cm²) Elogation E_(B) (%) 510 470 470 680 690 Thermalaging resistance 190° C. × 168 hrs. Tensile strength 65 68 64 40 38retention ratio A_(R) (T_(B)) (%) Elongation 78 70 72 58 56 retentionratio A_(R) (E_(B)) (%) A_(R) (T_(B) × E_(B)) (%) Processability Rollprocessability 5 5 5 5 5 Extrusion processability 5 5 5 5 5 Comp.Example Ex. 23 24 25 18 Composition (parts by weight) Copolymer rubber(A-1) (A1-1) — — 50 50 (A1-6) 50 — — — (A1-7) — 100 — — Copolymer rubber(A2) (A2-1) — — 50 50 (A2-6) 50 — — — Amine anti-aging agent (C) 1 1 1 1(C-1) Hindered phenol anti-aging agent (D) 1 1 1 1 (D-1) Sulphuranti-aging agent (E) 4 4 — 4 (E-1) Phosphite anti-aging agent — — 4 —4,4′-butylidenbis(3-methy- 6-t-butyl-di-tridecylphosphite) (F-1)Vulcanized rubber Original state Tensile strength 104 125 103 138 T_(B)(kgf/cm²) Elogation E_(B) (%) 670 680 480 550 Thermal aging resistance190° C. × 168 hrs. Tensile strength 32 40 15 64 retention ratio A_(R)(T_(B)) (%) Elongation retention 59 51 20 76 ratio A_(R) (E_(B)) (%)A_(R) (T_(B) × E_(B)) (%) Processability Roll processability 5 2 5 5Extrusion processability 5 1 5 5

Remark: In Example 18, 1 part by weight of Sanceler AP (Trademark,available from Sanshin Kagaku Kogyo K.K.) was added as vulcanization aidin addition to the above components.

What is claimed is:
 1. A heat-resistant rubber composition comprising:an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A) composedof ethylene, an α-olefin of 3 to 20 carbon atoms and a nonconjugatedpolyene, and an organic peroxide (B); and having vulcanizableproperties, said ethylene-α-olefin-nonconjugated polyene copolymerrubber (A) having the following properties: (1) a molar ratio ofethylene to the α-olefin of 3 to 20 carbon atoms is in the range of40/60 55/45 to 95/5 85/15 (ethylene/α-olefin), (2) the nonconjugatedpolyene is 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene or5-isobutenyl-2-norbornene, (3) the nonconjugated polyene content is inthe range of 0.5 to 50 g/100 g in terms of iodine value, and (4) anintrinsic viscosity (η), as measured in decahydronaphthalene at 135° C.,of 0.1 to 10 dl/g.
 2. A heat-resistant rubber composition comprising:(I) an ethylene-e-olefin-nonconjugated polyene copolymer rubber (A)composed of ethylene, an α-olefin of 3 to 20 carbon atoms and anonconjugated polyene, in an amount of 100 parts by weight, (II) anamine type anti-aging agent (C) composed of diphenylamines and/orphenylenediamines, in an amount of 0.2 to 5 parts by weight, and/or ahindered phenol type anti-aging agent (D) in an amount of 0.2 to 5 partsby weight, and (III) a sulfur type anti-aging agent (E) in an amount of1 to 10 parts by weight; and having vulcanizable properties, saidethylene-α-olefin-nonconjugated polyene copolymer rubber (A) having thefollowing properties: (1) a molar ratio of ethylene to the α-olefin of 3to 20 carbon atoms is in the range of 40/60 to 95/5 (ethylene/α-olefin),(2) the nonconjugated polyene is 5-vinyl-2-norbornene,5-isopropenyl-2-norbornene or 5-isobutenyl-2-norbornene, (3) thenonconjugated polyene content is in the range of 0.5 to 50 g/100 g interms of an iodine value, and (4) an intrinsic viscosity (η), asmeasured in decalin at 135° C., of 0.1 to 10 dl/g.
 3. The heat-resistantrubber composition as claimed in claim 2 wherein theethylene-.alpha.-olefin-nonconjugated polyene copolymer rubber (A) is ablend of: (I) an ethylene-α-olefin-nonconjugated polyene copolymerrubber (A1) having an intrinsic viscosity (η), as measured in decalin at135° C., of 1 to 10 dl/g, in an amount of 30 to 95 parts by weight, and(II) an ethylene-α-olefin-nonconjugated polyene copolymer rubber (A2)having an intrinsic viscosity (η), as measured in decalin at 135° C., of0.1 to 5 dl/g, this intrinsic viscosity being different from theintrinsic viscosity of the ethylene-α-olefin-nonconjugated polyenecopolymer rubber (A1), in an amount of 5 to 70 parts by weight, thetotal amount of said components (A1) and (A2) being 100 parts by weight;and said ethylene-α-olefin-nonconjugated polyene copolymer rubber (A1)having the following properties: (1) said copolymer rubber is acopolymer rubber composed of ethylene, an α-olefin of 3 to 20 carbonatoms and a nonconjugated polyene, (2) a molar ratio of ethylene to theα-olefin of 3 to 20 carbon atoms is in the range of 40/60 to 95/5(ethylene/α-olefin), (3) the nonconjugated polyene is5-vinyl-2-norbornene, and (4) the nonconjugated polyene content is inthe range of 0.5 to 50 g/100 g in terms of an iodine value; and saidethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) having thefollowing properties: (1) said copolymer rubber is a copolymer rubbercomposed of ethylene, an α-olefin of 3 to 20 carbon atoms and anonconjugated polyene, (2) a molar ratio of ethylene to the α-olefin of3 to 20 carbon atoms is in the range of 40/60 to 95/5(ethylene/α-olefin), (3) the nonconjugated polyene is5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene or5-isobutenyl-2-norbornene, and (4) the nonconjugated polyene content isin the range of 0.5 to 50 g/100 g in terms of an iodine value.
 4. Theheat-resistant rubber composition as claimed in claim 3, wherein theethylene-α-olefin-nonconjugated polyene copolymer rubber (A) which is ablend of the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A1) and the ethylene-α-olefin-nonconjugated polyene copolymer rubber(A2) has: (i) a Mooney viscosity (ML₁₊₄(100° C.)) of 5 to 180, (ii) amolar ratio of ethylene to the α-olefin of 40/60 to 95/5(ethylene/α-olefin), and (iii) a nonconjugated polyene content of 0.5 to50 g/100 g in terms of an iodine value.
 5. The heat-resistant rubbercomposition as claimed in claim 3 or claim 4, wherein theethylene-α-olefin-nonconjugated polyene copolymer rubber (A1) and/or theethylene-α-olefin-nonconjugated polyene copolymer rubber (A2) is anethylene-α-olefin-nonconjugated polyene copolymer rubber having beengraft-modified with an unsaturated carboxylic acid or its derivative. 6.The heat-resistant rubber composition according to claim 1 , wherein theα-olefin is propylene.
 7. The heat-resistant rubber compositionaccording to claim 2 , wherein the α-olefin is propylene.
 8. Theheat-resistant rubber composition according to claim 7 , wherein themolar ratio of ethylene to propylene is in the range of 55/45 to 85/15.9. The heat-resistant rubber composition according to claim 3 , whereinthe α-olefin in at least one of copolymer rubber (A1 ) and copolymerrubber (A2 ) is propylene.
 10. The heat-resistant rubber compositionaccording to claim 3 , wherein the α-olefin in each of copolymer rubber(A1 ) and copolymer rubber (A2 ) is propylene.
 11. The heat-resistantrubber composition according to claim 3 , wherein in at least one ofcopolymer rubber (A1 ) and copolymer rubber (A2 ), the molar ratio ofethylene to the α-olefin of from 3 to 20 carbon atoms is in the range offrom 55/45 to 85/15.
 12. The heat-resistant rubber composition accordingto claim 3 , wherein in each of copolymer rubbers (A1 ) and (A2 ) themolar ratio of ethylene to the α-olefin of 3 to 20 carbon atoms is from55/45 to 85/15.
 13. The heat-resistant rubber composition according toclaim 12 , wherein the α-olefin of 3 to 20 carbon atoms is propylene.14. A vulcanized composition obtained by vulcanizing the heat-resistantrubber composition according to any one of claims 1 to 3 or 6 to
 13. 15.A molded or foamed article obtained by molding or foaming theheat-resistant rubber composition according to any one of claim 1 to 3or 6 to
 13. 16. An automotive part comprising a heat-resistant rubbercomposition according to any one of claims 1, 2 or
 3. 17. An automotivepart according to claim 16, wherein the heat-resistant rubbercomposition is vulcanized.
 18. An automotive part according to claim 16,wherein the heat-resistant rubber composition is molded or foamed. 19.An automotive part according to claim 16, which is a door glass runchannel, and wherein the heat-resistant rubber composition maybevulcanized, molded or foamed.
 20. An automotive part according to claim16, which is a window frame, and wherein the heat-resistant rubbercomposition may be vulcanized, molded or foamed.
 21. An automotive partaccording to claim 16, which is a radiator hose, and wherein theheat-resistant rubber composition may be vulcanized, molded or foamed.22. An automotive part according to claim 16, which is a brake part, andwherein the heat-resistant rubber composition may be vulcanized, moldedor foamed.
 23. An automotive part according to claim 16, which is awiper blade, and wherein the heat-resistant rubber composition may bevulcanized, molded or foamed.
 24. An industrial rubber part comprising aheat-resistant rubber composition according to any one of claims 1, 2 or3.
 25. An industrial rubber part according to claim 24, wherein theheat-resistant rubber composition is vulcanized.
 26. An industrialrubber part according to claim 24, wherein the heat-resistant rubbercomposition is molded or foamed.
 27. An industrial rubber part accordingto claim 24, which is a rubber roll, and wherein the heat-resistantrubber composition may be vulcanized, molded or foamed.
 28. Anindustrial rubber part according to claim 24, which is a rubber belt,and wherein the heat-resistant rubber composition may be vulcanized,molded or foamed.
 29. An industrial rubber part according to claim 24,which is a rubber packing, and wherein the heat-resistant rubbercomposition may be vulcanized, molded or foamed.
 30. An industrialrubber part according to claim 24, which is a rubber hose, and whereinthe heat-resistant rubber composition may be vulcanized, molded orfoamed.
 31. An electrically insulating anode cap comprising theheat-resistant rubber composition of any one of claims 1, 2 or 3, andwherein said heat-resistant rubber composition may be vulcanized, moldedor foamed.
 32. An electrically insulating rubber grommet, comprising theheat-resistant rubber composition according to any one of claims 1, 2 or3, and wherein said heat-resistant rubber composition may be vulcanized,molded or foamed.
 33. A gasket for building materials comprising theheat-resistant rubber composition according to any one of claims 1, 2 or3, and wherein the heat-resistant rubber composition may be vulcanized,molded or foamed.